This is Doryphoros (Dore-IF-er-us), a statue created by the Greeks in the fifth century bc. He later came to be regarded by the Romans as the Canon of Proportion, or the ideal man. In fact, when it was time for Emperor Augustus to be immortalized in marble, he merely had his sculpted head placed on a copy of this body.

Needless to say, few sedentary men (let alone black men) are walking around with 52-inch muscular chests (or the height-adjusted equivalent). Here are twoposts at a sculpture website looking at classical canons of proportion in light of anthropometric data, the upshot being:

The “academic canon” lines up pretty well with the mean plus one standard deviation. The “ideal (Vitruvian) canon” matches up fairly close to the mean plus two standard deviations and the “heroic” nine heads canon matches up with the proportions of the population maximum.

"Their physical ability is obvious when looking at the physique of the average black and white man."

Ah, and there's the rub - what you see in the US is not the average black man, he is instead the descendant of African slaves who were chosen for their size and strength. What you see in white Americans on the other hand, are the descendants of a broad cross section of the white race which included big guys, little guys, and all the in betweens.